WAVE PATTERNS OF NON-THIN OR FULL-BODIED SHIPS

This paper presents a method for determining the wave pattern produced by the motion of a nonthin or full-bodied ship. It is based upon the assumption that the Froude number F=U2/gL is small, where U is the ship speed, L is the ship length and g is the acceleration of gravity. In this case the wavelength of the resulting waves is small compared to L. Therefore, the waves can be described by a theory like geometrical optics, in which rays, a phase function and an amplitude function play a role. The waves are superposed on the double body flow, which is the potential flow about the ship and its image in the undisturbed free surface. They are produced at the bow and stern, and travel outward and rearward from these points along curved rays, which become straight far from the ship. In addition, some waves from the bow travel along the surface at the waterline and leave it tangentially toward the rear along similar rays. Thus the ship wave pattern consists primarily of the waves from two sources, one at the bow and one at the stern. The results are confirmed by comparison with the small F asymptotic evaluation of Michell's solution for thin ships.